Source: RB James has dislocated elbow, will miss a month

Two days after backup running back Kendall Hunter sustained a torn ACL, LaMichael James suffered a dislocated left elbow during practice today and is expected to be sidelined a month, a source said. If so, James would likely miss the exhibition season – the preseason finale is Aug. 28 at Houston – but would be available for the season opener at Dallas on Sept. 7.

James, who missed two games with a dislocated right elbow at Oregon in 2011, was carted to the locker room after he was injured when he collided with inside linebacker Michael Wilhoite during a blitz-pickup drill. After James exited, Frank Gore was only running back left at practice who has played in an NFL game. The other running backs on the active roster are second-round pick Carlos Hyde and Jewel Hampton, who spent last year on the practice squad.

Marcus Lattimore (knee, hamstring) has spent the first four practices of training camp on the non-football injury list. Lattimore hasn’t played since he tore all three major ligaments in his knee at South Carolina in October 2012. On Saturday, general manager Trent Baalke said Lattimore, who participated in part of the offseason program, hadn’t suffered a setback.

“He’s coming off, as we all know, a horrific injury,” Baalke said. “We want to make sure — as does he — that he’s 100 percent mentally and physically ready to go to help this football team.”

James also finished 2013 as the team’s punt and kickoff returner. He averaged 10.9 yards per punt return, which ranked 14th in the NFL, and 26.8 yards on 12 kickoffs. Cornerback Perrish Cox and wide receiver Devon Wylie are candidates to fill-in at punt returner.

The 49ers will likely place Hunter on injured reserve and sign another running back. If nothing else, they will need another back to share the preseason workload. Gore has had four preseason carries in each of the past two seasons.

Quarterbacks Blaine Gabbert, (2), Josh Johnson, (1) and Colin Kaepernick, (7) warm up as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014

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Quarterbacks Blaine Gabbert, (2), Josh Johnson, (1) and Colin Kaepernick, (7) warm up as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014

Quarterbacks Blaine Gabbert, (2), Josh Johnson, (1) and Colin...Kaepernick, (7) warm up as the San Francisco 49ers hold training camp...to prepare for the 2014 season in Santa Clara, Calif., on Thursday...July 24, 2014

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Stanford standout Shane Skov, (44) among the defensive players on the team as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

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Stanford standout Shane Skov, (44) among the defensive players on the team as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

Stanford standout Shane Skov, (44) among the defensive players on the...team as the San Francisco 49ers hold training camp to prepare for the...2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

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Linebackers hit blocking dummies against the backdrop of the new Levi's Stadium, as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

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Linebackers hit blocking dummies against the backdrop of the new Levi's Stadium, as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

Linebackers hit blocking dummies against the backdrop of the new...Levi's Stadium, as the San Francisco 49ers hold training camp to...prepare for the 2014 season in Santa Clara, Calif., on Thursday July...24, 2014.

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Michael Macor / The Chronicle

Linebacker Patrick Willis, (52) runs drills as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

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Linebacker Patrick Willis, (52) runs drills as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

Linebacker Patrick Willis, (52) runs drills as the San Francisco...49ers hold training camp to prepare for the 2014 season in Santa...Clara, Calif., on Thursday July 24, 2014.

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The Chronicle

Defensive tackle Quinton Dial, (92) runs drills as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

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Defensive tackle Quinton Dial, (92) runs drills as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

Defensive tackle Quinton Dial, (92) runs drills as the San Francisco...49ers hold training camp to prepare for the 2014 season in Santa...Clara, Calif., on Thursday July 24, 2014.

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Quarterback McLeod Bethel-Thompson, (5) runs passing drills as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

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Quarterback McLeod Bethel-Thompson, (5) runs passing drills as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

Defensive tackle Quinton Dial, (92) takes a break as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

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Defensive tackle Quinton Dial, (92) takes a break as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

Defensive tackle Quinton Dial, (92) takes a break as the San Francisco...49ers hold training camp to prepare for the 2014 season in Santa...Clara, Calif., on Thursday July 24, 2014.

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Linebacker Patrick Willis, (52) and safety Antoine Bethea, (24) take a break as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

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Linebacker Patrick Willis, (52) and safety Antoine Bethea, (24) take a break as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

Linebacker Patrick Willis, (52) and safety Antoine Bethea, (24) take a...break as the San Francisco 49ers hold training camp to prepare for the...2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

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The Chronicle

Linebackers Ahmad Brooks, (55) and Aldon Smith, (99) run drills as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

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Linebackers Ahmad Brooks, (55) and Aldon Smith, (99) run drills as the San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

Wide receiver Anquan Boldin, (81) runs passing drills as San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

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Wide receiver Anquan Boldin, (81) runs passing drills as San Francisco 49ers hold training camp to prepare for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

Wide receiver Anquan Boldin, (81) runs passing drills as San Francisco...49ers hold training camp to prepare for the 2014 season in Santa...Clara, Calif., on Thursday July 24, 2014.

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Michael Macor / The Chronicle

San Francisco 49ers' Aldon Smith, (99) speaks to the media on Thursday July 24, 2014 during training camp as the team prepares for the 2014 season in Santa Clara, Calif.

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San Francisco 49ers' Aldon Smith, (99) speaks to the media on Thursday July 24, 2014 during training camp as the team prepares for the 2014 season in Santa Clara, Calif.

San Francisco 49ers' Aldon Smith, (99) speaks to the media on Thursday...July 24, 2014 during training camp as the team prepares for the 2014...season in Santa Clara, Calif.

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Michael Macor / The Chronicle

San Francisco 49ers' Aldon Smith, (99) speaks to the media on Thursday July 24, 2014 during training camp as the team prepares for the 2014 season in Santa Clara, Calif.

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San Francisco 49ers' Aldon Smith, (99) speaks to the media on Thursday July 24, 2014 during training camp as the team prepares for the 2014 season in Santa Clara, Calif.

San Francisco 49ers' Aldon Smith, (99) speaks to the media on Thursday...July 24, 2014 during training camp as the team prepares for the 2014...season in Santa Clara, Calif.

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Michael Macor / The Chronicle

San Francisco 49ers' tight end Vernon Davis,(85) as seen on Thursday July 24, 2014 during training camp as the team prepares for the 2014 season in Santa Clara, Calif.

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San Francisco 49ers' tight end Vernon Davis,(85) as seen on Thursday July 24, 2014 during training camp as the team prepares for the 2014 season in Santa Clara, Calif.

San Francisco 49ers' tight end Vernon Davis,(85) as seen on Thursday...July 24, 2014 during training camp as the team prepares for the 2014...season in Santa Clara, Calif.

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Michael Macor / The Chronicle

San Francisco 49ers head coach Jim Harbaugh leaves the podium after holding his first press conference in the new Levi's Stadium, on Thursday July 24, 2014 during training camp as the team prepares for the 2014 season in Santa Clara, Calif.

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San Francisco 49ers head coach Jim Harbaugh leaves the podium after holding his first press conference in the new Levi's Stadium, on Thursday July 24, 2014 during training camp as the team prepares for the 2014 season in Santa Clara, Calif.

San Francisco 49ers head coach Jim Harbaugh leaves the podium after...holding his first press conference in the new Levi's Stadium, on...Thursday July 24, 2014 during training camp as the team prepares for...the 2014 season in Santa Clara, Calif.

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Michael Macor / The Chronicle

San Francisco 49ers' tight end Vernon Davis,(85) after speaking with the media on Thursday July 24, 2014 during training camp as the team prepares for the 2014 season in Santa Clara, Calif.

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San Francisco 49ers' tight end Vernon Davis,(85) after speaking with the media on Thursday July 24, 2014 during training camp as the team prepares for the 2014 season in Santa Clara, Calif.

San Francisco 49ers' tight end Vernon Davis,(85) after speaking with...the media on Thursday July 24, 2014 during training camp as the team...prepares for the 2014 season in Santa Clara, Calif.

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Michael Macor / The Chronicle

San Francisco 49ers head coach Jim Harbaugh holds his first press conference in the new Levi's Stadium during training camp as the team prepares for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

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San Francisco 49ers head coach Jim Harbaugh holds his first press conference in the new Levi's Stadium during training camp as the team prepares for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

San Francisco 49ers head coach Jim Harbaugh holds his first press...conference in the new Levi's Stadium during training camp as the team...prepares for the 2014 season in Santa Clara, Calif., on Thursday July...24, 2014.

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Michael Macor / The Chronicle

San Francisco 49ers head coach Jim Harbaugh holds his first press conference in the new Levi's Stadium during training camp as the team prepares for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

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San Francisco 49ers head coach Jim Harbaugh holds his first press conference in the new Levi's Stadium during training camp as the team prepares for the 2014 season in Santa Clara, Calif., on Thursday July 24, 2014.

San Francisco 49ers head coach Jim Harbaugh holds his first press...conference in the new Levi's Stadium during training camp as the team...prepares for the 2014 season in Santa Clara, Calif., on Thursday July...24, 2014.

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Michael Macor / The Chronicle

Justin Smith, (94) wears a tee shirt showing their defensive line as the San Francisco 49ers' veterans reported to training camp today for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Justin Smith, (94) wears a tee shirt showing their defensive line as the San Francisco 49ers' veterans reported to training camp today for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

Quarterback Colin Kaepernick, (7) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Quarterback Colin Kaepernick, (7) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

Quarterback Colin Kaepernick, (7) talks with the news media as the San...Francisco 49ers' veteran players reported to training camp today to...prepare for the 2014 season at their practice facility in Santa Clara,...Calif., as seen on Wednesday July 23, 2014.

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Michael Macor / The Chronicle

Linebacker Patrick Willis, (52) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Linebacker Patrick Willis, (52) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

Linebacker Patrick Willis, (52) talks with the news media as the San...Francisco 49ers' veteran players reported to training camp today to...prepare for the 2014 season at their practice facility in Santa Clara,...Calif., as seen on Wednesday July 23, 2014.

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Michael Macor / The Chronicle

Running back Frank Gore, (21) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Running back Frank Gore, (21) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

Running back Frank Gore, (21) talks with the news media as the San...Francisco 49ers' veteran players reported to training camp today to...prepare for the 2014 season at their practice facility in Santa Clara,...Calif., as seen on Wednesday July 23, 2014.

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Michael Macor / The Chronicle

Quarterback Colin Kaepernick, (7) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Quarterback Colin Kaepernick, (7) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

Quarterback Colin Kaepernick, (7) talks with the news media as the San...Francisco 49ers' veteran players reported to training camp today to...prepare for the 2014 season at their practice facility in Santa Clara,...Calif., as seen on Wednesday July 23, 2014.

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Michael Macor / The Chronicle

Wide receiver Stevie Johnson, (13) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Wide receiver Stevie Johnson, (13) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

Wide receiver Stevie Johnson, (13) talks with the news media as the...San Francisco 49ers' veteran players reported to training camp today...to prepare for the 2014 season at their practice facility in Santa...Clara, Calif., as seen on Wednesday July 23, 2014.

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Michael Macor / The Chronicle

Quarterback Colin Kaepernick, (7) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Quarterback Colin Kaepernick, (7) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

Quarterback Colin Kaepernick, (7) talks with the news media as the San...Francisco 49ers' veteran players reported to training camp today to...prepare for the 2014 season at their practice facility in Santa Clara,...Calif., as seen on Wednesday July 23, 2014.

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Michael Macor / The Chronicle

Running back Frank Gore, (21) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Running back Frank Gore, (21) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

Running back Frank Gore, (21) talks with the news media as the San...Francisco 49ers' veteran players reported to training camp today to...prepare for the 2014 season at their practice facility in Santa Clara,...Calif., as seen on Wednesday July 23, 2014.

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Michael Macor / The Chronicle

Wide receiver Stevie Johnson, (13) prepares to talk with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Wide receiver Stevie Johnson, (13) prepares to talk with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

Wide receiver Stevie Johnson, (13) prepares to talk with the news...media as the San Francisco 49ers' veteran players reported to training...camp today to prepare for the 2014 season at their practice facility...in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Michael Macor / The Chronicle

Wide receiver Stevie Johnson, (13) talks with the news media as the San Francisco 49ers' veterans reported to training camp today for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Wide receiver Stevie Johnson, (13) talks with the news media as the San Francisco 49ers' veterans reported to training camp today for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

Justin Smith, (94) talks with the media as the San Francisco 49ers' veterans reported to training camp today for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Justin Smith, (94) talks with the media as the San Francisco 49ers' veterans reported to training camp today for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

Justin Smith, (94) talks with the media as the San Francisco 49ers'...veterans reported to training camp today for the 2014 season at their...practice facility in Santa Clara, Calif., as seen on Wednesday July...23, 2014.

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Michael Macor / The Chronicle

Linebacker Patrick Willis, (52) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Linebacker Patrick Willis, (52) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

Linebacker Patrick Willis, (52) talks with the news media as the San...Francisco 49ers' veteran players reported to training camp today to...prepare for the 2014 season at their practice facility in Santa Clara,...Calif., as seen on Wednesday July 23, 2014.

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Michael Macor / The Chronicle

Quarterback Colin Kaepernick, (7) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

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Quarterback Colin Kaepernick, (7) talks with the news media as the San Francisco 49ers' veteran players reported to training camp today to prepare for the 2014 season at their practice facility in Santa Clara, Calif., as seen on Wednesday July 23, 2014.

Quarterback Colin Kaepernick, (7) talks with the news media as the San...Francisco 49ers' veteran players reported to training camp today to...prepare for the 2014 season at their practice facility in Santa Clara,...Calif., as seen on Wednesday July 23, 2014.